Image Processing

indifferenthappylandAI and Robotics

Nov 6, 2013 (3 years and 9 months ago)

85 views

11/6/2013

1

Image Processing

11/6/2013

2

Systems and Software


Image file formats


Image processing applications

11/6/2013

3

Image file formats


Pixel images


Graphic images


Composite image files


Images in manuscripts

Graphic

11/6/2013

4

Format issues


Color, monochrome


Capability


Gray value


Graphics


Calibration: size, sensitometry, etc...


Compatibility


Compression

11/6/2013

5

Common formats


TIFF


Common usage


Versatile: pixel, calibration


Pixel
-
based regions


Dialects


Raw


EPS


versatile


primarily, printed document format


PICT, PICS


well developed standard


pixel and graphic format


primarily Macintosh

11/6/2013

6

Common formats (more)


DICOM


used in medical imaging


Graphic arts:


MPEG, JPEG, GIF

Import menu in

NIH Image

11/6/2013

7

Image processing software functions


Image acquisition


Image processing


Quantitative data extraction


Annotation and editing


Database management


File format conversion

11/6/2013

8

Image processing software structure


Task
-
dedicated


General purpose


Scripting/macro language

11/6/2013

9

Software package examples


NIH Image


http://rsb.info.nih.gov/nih
-
image/


Adobe Photoshop

11/6/2013

10

Examples


NIH Image & file conversion


Annotation


Copying, pasting

11/6/2013

11

Software selection issues


Compatibility with computer


Functionality


Control of acquisition hardware (compatibility)


Range of processing algorithms


Productivity

11/6/2013

12

Image processing


Contrast manipulation and enhancement


Dyadic operation


Image filtering


Regions and region operation


Image analysis

11/6/2013

13

Monadic (one picture) operations


Contrast manipulation and enhancement


LUT operation


brightness, contrast


False color


Gray value remap (apply LUT)


Arithmetic operations


Scale and rotate (also morphing)


Other single image operations

11/6/2013

14

Monadic operations


Profile plot (and projection)


Gray value histogram

11/6/2013

15

Display operations


Gray scale manipulation





False color manipulation


Enlarge, contract, scale to fit window

See
Adobe Illustrator

for image editing

11/6/2013

16

(a)

(b)

(c)

(a) Original image, (b) rotated by 1.2
°
, nearest neighbor
interpolation, (c) rotated by 1.2
°
, bilinear interpolation.

11/6/2013

17

Examples of histograms

11/6/2013

18

Dyadic (two image) operations

Dyadic (two variable) function:

Examples: addition, multiplication, subtraction, and division.


Problem: finite numerical range fro picture gray value leads


to roundoff.

11/6/2013

19

Example: shading correction

11/6/2013

20

Image Filtering


Convolution


Rank filtering


Edge detection

11/6/2013

21

Image filtering (conceptual)

11/6/2013

22

Convolution with the Fourier transform

11/6/2013

23

Examples of linear filters


Low
-
pass (smooth, Gauss)


High
-
pass (sharpen, Mexican Hat, DOG)


Shadow


First derivative (shadow, find edges)

11/6/2013

24

Example of smoothing

Smoothing (5 times)

Before

After

11/6/2013

25

Convolve

Original

Gauss (7x7)

‘Mexican hat’(17x17)

Grad N

Grad W

11/6/2013

26

Nonlinear filters


Median (noise eliminate and enhance)


Minimum (erode)


Maximum (dilate)


Open


Close

11/6/2013

27

Example of morphological (rank) filters

Opening (3)

Closing (3)

Original

Minimum,

erode (1)

Maximum,

dilate (1)

11/6/2013

28

Example, grain counting

Grain image

Maximum (5)

Difference

11/6/2013

29

Regions and region operation


Thresholding, density slicing


Erosion, dilation (rank filtering)


Skeletons

11/6/2013

30

Image analysis


Sensitometric


Geometric


Categorical (image recognition)

11/6/2013

31

Segmentation


Geometrical shapes


Interactive (outlining)


Thresholding


Filling

11/6/2013

32

Segmentation
-

connected area

Density slice, then use wand (auto
-
outline) to trace outline.

Outline written on image with ‘draw boundary’ command.

11/6/2013

33

Region of interest (ROI) analysis


Area


Perimeter


Shape


Average value


Standard deviation

11/6/2013

34

Example of measurement

126.00


132.48


39.27


14.37


11.16

Area

Mean

Length

Minor

Major

11/6/2013

35

Summary


Paradigm: scanning, preprocessing, analysis


Success depends on all parts of analysis chain


Quality control


Quantitative evaluation of performance


Test samples


Repeated analysis

11/6/2013

36

Summary


Digital image acquisition
-

physical data to numbers


Control of accuracy

Experimental design

Experimental preparation

Scanner


Scanner in the lab

Complex device, operation and maintenance

Quality control mandatory

11/6/2013

37

Houston, we have a problem.